Masanobu Hiroki and Kazuhide Kumakura

NTT Basic Research Laboratories, NTT Corporation, Atsugi 243-0198, Japan

 

Thermal management is a key factor in achieving high-power performance in GaN-based HEMTs. Transferring the HEMTs to a foreign substrate with high thermal conductivity is a challenging but promising approach for efficient heat dissipation, which provides us a free hand to choose material as a substrate. We have been developing an epitaxial lift-off and transfer technique using ultra-thin h-BN release layers [1,2]. Using this substrate-transfer technique, we have transferred AlGaN/GaN HEMTs from host sapphire substrate to foreign substrates with high thermal conductivity such as copper, SiC and diamond.

  The device temperature and dc performance of the AlGaN/GaN HEMTs before and after transfer were clarified. The temperature in the active region of the HEMTs before transfer was 240ºC at power dissipation of 0.8 W, while it was as small as 70 ºC after transfer. As a result, the maximum drain current increased from 0.54 to 0.67 A/mm. The obtained results indicate that the substrate-transfer technique can enhance heat dissipation and boost the power performance of HEMTs.

 

[1] 1 Y. Kobayashi et al., Nature 484, 223 (2012).

[2] M. Hiroki et al., Appl. Phys. Lett. 105, 193509 (2014).